Geological Research at the IGS
Data compilation and analysis for the Coastal Nonpoint Source Management Plan
||Jun 3, 2004
||Aug 3, 2005
Lake, LaPorte, Porter
Sally L. Letsinger and Greg A. Olyphant
Indiana Department of Environmental Management (IDEM)
||According to the Lake Michigan Lakewide Management Plan, although 20 years of regulation brought an overall reduction in pollutant loads to the Lake Michigan basin, data indicate pollutants still negatively impact the chemical, physical, and biological components of the Lake Michigan ecosystem. The rivers and tributaries flowing into Lake Michigan convey contaminants from their source areas. This study describes the monitoring efforts attempted to characterize the quality of surface water in the Coastal Nonpoint Pollution Control Plan Area (CNPCPA).
||This study documented the surface-water quality monitoring efforts that have occurred in the subwatersheds of the Coastal Nonpoint Pollution Control Plan Area. The data were analyzed to assess water-quality trends occurring in the program area. Results from this analysis were used to develop a monitoring plan for Indianas Coastal Nonpoint Source Management Plan.
||For this project, all water-quality data available from the following sources were assembled into a database.
In an effort to determine if, and how many, trends are evident in the data base, we subjected all data sets having more than 20 samples to multiple regression analysis. Of the 1,079 water quality attributes that were analyzed for trend, 536 (50%) exhibited a statistically significant time trend. Of those, 278 (52%) were positive trends (declining water quality) and 258 (48%) were negative trends (improving water quality).
To aid the process of prioritizing additional reaches for water-quality trend monitoring, a decision tree was developed. The decision tree can be used to aid in the selection of new monitoring sites, and to identify sites that represent an opportunity for reduction in sampling efforts when funding resources are limited.
||The final report submitted to the Indiana Department of Environmental Management includes maps, graphs, and written analyses regarding the water-quality trends in the Lake Michigan Coastal Nonpoint Control Plan Area.
||Results-driven recommendations were provided to the agency regarding prioritizing fixed-station monitoring locations.